The present invention relates to a transfer method and apparatus, which use a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, and which transfer the partial transfer patterns onto a transfer medium in turn, and consequently transfer a pattern obtained by joining the plurality of partial patterns, and a method of manufacturing a device using the transfer method.
As semiconductor devices continue to shrink in feature size and their performance and functions improve, lithography apparatuses now have higher resolutions and larger field angles, and the transfer scheme is changing to the step-and-scan scheme via the full wafer scheme and step-and-repeat scheme. In such a trend, even in an exposure apparatus that uses a charged beam such as an electron beam that can expect higher resolution, a scan reduction transfer system that uses a transfer mask has been proposed.
However, in such apparatus, a divided mask obtained by dividing a transfer pattern into a plurality of partial transfer patterns is used owing to considerable drop of image performance upon broadening of the field angle, limitations on the structure of a mask used, and the like, and these divided patterns are transferred while they are joined in turn, thus obtaining a desired pattern.
The divided mask is obtained by lining up divided partial transfer patterns at predetermined positions on a single mask substrate, and is formed on, e.g., a silicon wafer by the same technique as a semiconductor process such as lithography, etching, or the like.
In a transfer method using the divided mask, since the joint precision between neighboring partial transfer patterns is important, the divided partial transfer patterns must be lined up at predetermined positions on the mask with very high precision. However, these partial transfer patterns of the divided mask and their matrix suffer geometrical errors produced during mask formation, such as a matrix error, rotation error, magnification error, orthogonality error, distortion, and the like. Furthermore, these errors are also caused by distortions of the divided mask due to changes in temperature, mechanical stress, aging, and the like. These errors impair the aforementioned joint precision, and defects are consequently produced in the chip obtained.
In order to solve such problem, as disclosed in Japanese Patent No. 2647835, the position of the overall mask is obtained using dedicated marks, and the next partial transfer pattern to be transferred by exposure is driven to the exposure position using a virtual coordinate system obtained based on the position data of the mask. After that, using alignment marks dedicated to the partial transfer patterns, the patterns are aligned pattern by pattern. Such method is called the dye-by-dye method, and is capable of accurate alignment since it aligns pattern by pattern.
However, with the aforementioned method, after each partial transfer pattern is temporarily driven using the virtual coordinate system, partial transfer patterns are aligned pattern by pattern using alignment marks dedicated to those patterns. Hence, measurement and driving processes for alignment are required upon transferring each partial transfer pattern, and these measurement and driving times lower the throughput of the overall apparatus. This problem has larger influences on the throughput as the number of divisions of the mask increases.
Furthermore, with the aforementioned method, a so-called 2nd layer requires alignment marks on a transfer medium, i.e., a wafer. However, depending on the way the transfer mask is divided, the wafer does not often have any marks corresponding to a partial transfer pattern on the transfer mask. For example, when a transfer pattern is divided into partial transfer patterns in a 5xc3x975 matrix, since partial transfer patterns in a 3xc3x973 matrix near the center of the matrix are present inside the actual element pattern region, it is impossible to transfer alignment marks to this region in advance. Hence, in practice, alignment cannot be done by the above-mentioned method.
It is, therefore, an object of the present invention to provide a mask pattern transfer method and apparatus, device manufacturing method, and transfer mask, which can improve the joint precision of partial transfer patterns upon obtaining a desired pattern by sequentially transferring a plurality of divided partial transfer patterns onto a transfer medium.
According to the first aspect of the present invention, a transfer method which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium, and consequently transfers a pattern obtained by joining the plurality of transfer patterns, comprises: the measurement step of measuring positions of the alignment marks formed on the transfer mask; the coordinate system determination step of determining an actual coordinate system of the plurality of partial transfer patterns formed on the transfer mask on the basis of measurement results in the measurement step; and the alignment step of sequentially aligning the partial transfer patterns to the transfer medium on the basis of the actual coordinate system determined in the coordinate system determination step, and transfer is done every time alignment is made in the alignment step.
In the transfer method according to the first aspect of the present invention, for example, the alignment step preferably has the parameter calculation step of calculating parameters that represent a relationship between the actual coordinate system of the plurality of partial transfer patterns and a design coordinate system of the plurality of partial transfer patterns, and includes the step of sequentially aligning the partial transfer patterns to the transfer medium on the basis of the parameters.
The transfer method according to the first aspect of the present invention, preferably further comprises the step of calculating a fabrication coordinate system of the plurality of transfer patterns; and correcting the actual coordinate system on the basis of the fabrication coordinate system, and the parameter calculation step includes the step of calculating parameters that represent a relationship between the corrected actual coordinate system and the design coordinate system.
In the transfer method according to the first aspect of the present invention, for example, the correction step preferably includes the step of calculating a difference between an actual position and design position of each of the partial transfer patterns and correcting the actual coordinate system on the basis of the difference.
In the transfer method according to the first aspect of the present invention, for example, the alignment step preferably further has the transfer position determination step of determining positions of the partial transfer patterns and the transfer medium upon transferring the partial transfer patterns onto the transfer medium on the basis of the parameters, and includes the step of moving the corresponding pattern and the transfer medium in turn to the positions determined in units of partial transfer patterns.
The transfer method according to the first aspect of the present invention preferably further comprises the designation step of designating the alignment marks to be measured in the measurement step of the transfer mask, and the measurement step includes the step of measuring the positions of the alignment marks designated in the designation step.
The transfer method according to the first aspect of the present invention preferably further comprises the profile calculation step of calculating profiles that indicate discrepancy levels between design and actual partial transfer patterns in units of partial transfer patterns on the basis of the measurement results in the measurement step, and the alignment step has the correction step of matching the actual partial transfer pattern with the corresponding design partial transfer pattern by moving the transfer mask on the basis of the calculated profiles every time the partial transfer pattern is transferred.
The transfer method according to the first aspect of the present invention preferably further comprises the profile calculation step of calculating profiles that indicate rotation amounts and/or magnifications between design and actual partial transfer patterns in units of partial transfer patterns on the basis of the measurement results in the measurement step, and the alignment step has the correction step of matching the actual partial transfer pattern with the corresponding design partial transfer pattern by moving the transfer mask on the basis of the calculated profiles every time the partial transfer pattern is transferred.
The transfer method according to the first aspect of the present invention preferably further comprises the profile calculation step of calculating a profile that represents discrepancy levels between design and actual partial transfer patterns on the basis of the measurement results in the measurement step, and the alignment step has the correction step of matching a plurality of actual partial transfer patterns with a plurality of design partial transfer patterns by moving the transfer mask on the basis of the calculated profile.
The transfer method according to the first aspect of the present invention preferably further comprises the profile calculation step of calculating a profile that represents rotation amounts and/or magnifications between design and actual partial transfer patterns on the basis of the measurement results in the measurement step, and the alignment step has the correction step of matching a plurality of actual partial transfer patterns with a plurality of design partial transfer patterns by moving the transfer mask on the basis of the calculated profile.
In the transfer method according to the first aspect of the present invention, for example, a charged beam is preferably used upon transferring the partial transfer patterns in turn onto the transfer medium.
In the transfer method according to the first aspect of the present invention, for example, a charged beam having an arcuated section is preferably used upon transferring the partial transfer patterns in turn onto the transfer medium.
According to the second aspect of the present invention, a transfer method which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium formed with a lower-layer pattern and a plurality of alignment marks, and consequently transfers an upper-layer pattern obtained by joining the plurality of transfer patterns to overlap the lower-layer pattern on the transfer medium, comprises: the first measurement step of measuring positions of the alignment marks formed on the transfer mask; the first coordinate system determination step of determining a first coordinate system as an actual coordinate system of the plurality of partial transfer patterns formed on the transfer mask on the basis of measurement results in the first measurement step; the second measurement step of measuring positions of the alignment marks formed on the transfer medium; the second coordinate system determination step of determining a second coordinate system as an actual coordinate system of the lower-layer pattern on the transfer medium on the basis of measurement results in the second measurement step; and the alignment step of sequentially aligning the partial transfer patterns to the lower-layer pattern on the basis of the first and second coordinate systems, and transfer is done every time alignment is made in the alignment step.
In the transfer method according to the second aspect of the present invention, for example, the alignment step preferably includes the step of sequentially aligning the partial transfer patterns to the transfer medium while correcting positions of the transfer mask and transfer medium to match both the first and second coordinate systems with a reference coordinate system.
The transfer method according to the second aspect of the present invention preferably further comprises: the first parameter calculation step of calculating first parameters that represent a relationship between the first coordinate system and a reference coordinate system; and the second parameter calculation step of calculating second parameters that represent a relationship between the second coordinate system and the reference coordinate system, and the alignment step includes the step of sequentially aligning the partial transfer patterns to the transfer medium on the basis of the first and second parameters.
The transfer method according to the second aspect of the present invention, preferably further comprises the steps of: calculating a fabrication coordinate system of the plurality of transfer patterns; and correcting the first coordinate system on the basis of the fabrication coordinate system, and the first parameter calculation step includes the step of calculating first parameters that represent a relationship between the corrected first coordinate system and the reference coordinate system.
In the transfer method according to the second aspect of the present invention, for example, the correction step preferably includes the step of calculating a difference between an actual position and design position of each of the partial transfer patterns and correcting the first coordinate system on the basis of the difference.
In the transfer method according to the second aspect of the present invention, for example, the alignment step preferably has: the first transfer position determination step of determining positions to which the partial transfer patterns are to be moved upon transferring the partial transfer patterns onto the transfer medium in units of partial transfer patterns on the basis of the first parameters; and the second transfer position determination step of determining positions to which the transfer medium is to be moved upon transferring the partial transfer patterns onto the transfer medium in units of partial transfer patterns on the basis of the second parameters, and the alignment step includes the step of moving the corresponding partial transfer pattern and transfer medium to the positions determined in the first and second transfer position determination steps every time the partial transfer pattern is transferred.
The transfer method according to the second aspect of the present invention preferably further comprises the designation step of designating the alignment marks to be measured in the first measurement step of the transfer mask, and the first measurement step includes the step of measuring positions of the alignment marks designated in the designation step.
The transfer method according to the second aspect of the present invention preferably further comprises the designation step of designating the alignment marks to be measured in the second measurement step of the transfer medium, and the second measurement step includes the step of measuring positions of the alignment marks designated in the designation step.
The transfer method according to the second aspect of the present invention preferably further comprises: the first designation step of designating the alignment marks to be measured in the first measurement step of the transfer mask; and the second designation step of designating the alignment marks to be measured in the second measurement step of the transfer medium, and the first measurement step includes the step of measuring positions of the alignment marks designated in the first designation step, and the second measurement step includes the step of measuring positions of the alignment marks designated in the second designation step.
The transfer method according to the second aspect of the present invention preferably further comprises the profile calculation step of calculating profiles that indicate discrepancy levels between design and actual partial transfer patterns in units of partial transfer patterns on the basis of the measurement results in the first measurement step, and the alignment step has the correction step of matching the actual partial transfer pattern with the corresponding design partial transfer pattern by moving the transfer mask on the basis of the calculated profiles every time the partial transfer pattern is transferred.
The transfer method according to the second aspect of the present invention preferably further comprises the profile calculation step of calculating profiles that indicate rotation amounts and/or magnifications between design and actual partial transfer patterns in units of partial transfer patterns on the basis of the measurement results in the first measurement step, and the alignment step has the correction step of matching the actual partial transfer pattern with the corresponding design partial transfer pattern by moving the transfer mask on the basis of the calculated profiles every time the partial transfer pattern is transferred.
The transfer method according to the second aspect of the present invention preferably further comprises the profile calculation step of calculating a profile that represents discrepancy levels between design and actual partial transfer patterns on the basis of the measurement results in the first measurement step, and the alignment step has the correction step of matching a plurality of actual partial transfer patterns with a plurality of design partial transfer patterns by moving the transfer mask on the basis of the calculated profile.
In the transfer method according to the second aspect of the present invention, for example, the lower-layer pattern formed on the transfer medium is formed using a transfer mask for a lower layer having a plurality of partial transfer patterns to be joined on the transfer medium, and alignment marks corresponding to the partial transfer patterns, and the transfer medium is formed with alignment marks in correspondence with a plurality of partial patterns formed by transferring the plurality of partial transfer patterns, the method preferably further comprises the calculation step of calculating profiles that indicate discrepancy levels between design and actual partial patterns on the transfer medium in units of partial patterns on the basis of the measurement results in the second measurement step, and the alignment step preferably has the correction step of correcting an image to be transferred onto the transfer medium via the corresponding partial transfer pattern on the basis of the calculated profiles every time the partial transfer pattern is transferred, thereby aligning the corresponding partial transfer pattern to the corresponding partial pattern on the transfer medium.
In the transfer method according to the second aspect of the present invention, for example, the lower-layer pattern formed on the transfer medium is formed using a transfer mask for a lower layer having a plurality of partial transfer patterns to be joined on the transfer medium, and alignment marks corresponding to the partial transfer patterns, and the transfer medium is formed with alignment marks in correspondence with a plurality of partial patterns formed by transferring the plurality of partial transfer patterns, the method preferably further comprises the calculation step of calculating profiles that indicate rotation amounts and/or magnifications between design and actual partial patterns on the transfer medium in units of partial patterns on the basis of the measurement results in the second measurement step, and the alignment step preferably has the correction step of correcting an image to be transferred onto the transfer medium via the corresponding partial transfer pattern on the basis of the calculated profiles every time the partial transfer pattern is transferred, thereby aligning the corresponding partial transfer pattern to the corresponding partial pattern on the transfer medium.
In the transfer method according to the second aspect of the present invention, for example, the lower-layer pattern formed on the transfer medium is formed using a transfer mask for a lower layer having a plurality of partial transfer patterns to be joined on the transfer medium, and alignment marks corresponding to the partial transfer patterns, and the transfer medium is formed with alignment marks in correspondence with a plurality of partial patterns formed by transferring the plurality of partial transfer patterns, the method preferably further comprises the calculation step of calculating a profile that represents discrepancy levels between design and actual partial patterns on the transfer medium on the basis of the measurement results in the second measurement step, and the alignment step preferably has the correction step of commonly correcting a plurality of images to be transferred onto the transfer medium via the plurality of partial transfer patterns on the basis of the calculated profile, thereby aligning the partial transfer patterns to the corresponding partial patterns on the transfer medium.
In the transfer method according to the second aspect of the present invention, for example, the lower-layer pattern formed on the transfer medium is formed using a transfer mask for a lower layer having a plurality of partial transfer patterns to be joined on the transfer medium, and alignment marks corresponding to the partial transfer patterns, and the transfer medium is formed with alignment marks in correspondence with a plurality of partial patterns formed by transferring the plurality of partial transfer patterns, the method preferably further comprises: the first profile calculation step of calculating first profiles that represent discrepancy levels between design and actual partial transfer patterns on the basis of the measurement results in the first measurement step; and the calculation step of calculating second profiles that represent discrepancy levels between design and actual partial patterns on the transfer medium on the basis of the measurement results in the second measurement step, and the alignment step preferably has: the first correction step of matching each of the actual partial transfer pattern with the corresponding design partial transfer pattern by moving the transfer mask on the basis of the calculated first profiles; and the second correction step of correcting an image to be transferred onto the transfer medium via each of the partial transfer patterns on the basis of the calculated second profiles, thereby aligning the partial transfer patterns to the corresponding partial patterns on the transfer medium.
In the transfer method according to the second aspect of the present invention, for example, a charged beam is preferably used upon transferring the partial transfer patterns in turn onto the transfer medium.
In the transfer method according to the second aspect of the present invention, for example, a charged beam having an arcuated section is preferably used upon transferring the partial transfer patterns in turn onto the transfer medium.
According to the third aspect of the present invention, a transfer method which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium, and consequently transfers a pattern obtained by joining the plurality of transfer patterns, comprises: the dividing step of dividing the plurality of partial transfer patterns into a plurality of groups; the measurement step of measuring positions of the alignment marks corresponding to the partial transfer patterns that belong to the divided groups; the coordinate system determination step of determining actual coordinate systems of the partial transfer patterns that belong to the groups on the basis of measurement results in the measurement step; and the alignment step of sequentially aligning the partial transfer patterns that belong to the group of interest to the transfer medium in units of groups on the basis of the coordinate system of the group of interest determined in the coordinate system determination step, and transfer is done every time alignment is made in the alignment step.
According to the fourth aspect of the present invention, a transfer method which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium, and consequently transfers a pattern obtained by joining the plurality of transfer patterns, comprises: the dividing step of dividing the plurality of partial transfer patterns into a plurality of groups, and executing, in units of groups: the measurement step of measuring positions of the alignment marks corresponding to the partial transfer patterns that belong to the group of interest; the coordinate system determination step of determining actual coordinate systems of the partial transfer patterns that belong to the group of interest on the basis of measurement results in the measurement step; and the alignment step of sequentially aligning the partial transfer patterns that belong to the group of interest to the transfer medium on the basis of the coordinate system of the group of interest determined in the coordinate system determination step, and transfer is done every time alignment is made in the alignment step.
According to the fifth aspect of the present invention, a transfer apparatus which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium, and consequently transfers a pattern obtained by joining the plurality of transfer patterns, comprises: measurement means for measuring positions of the alignment marks formed on the transfer mask; coordinate system determination means for determining an actual coordinate system of the plurality of partial transfer patterns formed on the transfer mask on the basis of measurement results of the measurement means; and alignment means for sequentially aligning the partial transfer patterns to the transfer medium on the basis of the actual coordinate system determined by the coordinate system determination means, and transfer is done every time alignment is made by the alignment means.
According to the sixth aspect of the present invention, a transfer apparatus which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium formed with a lower-layer pattern and a plurality of alignment marks, and consequently transfers an upper-layer pattern obtained by joining the plurality of transfer patterns to overlap the lower-layer pattern on the transfer medium, comprises: first measurement means for measuring positions of the alignment marks formed on the transfer mask; first coordinate system determination means for determining a first coordinate system as an actual coordinate system of the plurality of partial transfer patterns formed on the transfer mask on the basis of measurement results of the first measurement means; second measurement means for measuring positions of the alignment marks formed on the transfer medium; second coordinate system determination means for determining a second coordinate system as an actual coordinate system of the lower-layer pattern on the transfer medium on the basis of measurement results of the second measurement means; and alignment means for sequentially aligning the partial transfer patterns to the lower-layer pattern on the basis of the first and second coordinate systems, and transfer is done every time alignment is made by the alignment means.
According to the seventh aspect of the present invention, a transfer apparatus which uses a transfer mask formed with a plurality of partial transfer patterns and a plurality of alignment marks, transfers the partial transfer patterns in turn onto a transfer medium, and consequently transfers a pattern obtained by joining the plurality of transfer patterns, comprises: dividing means for dividing the plurality of partial transfer patterns into a plurality of groups; measurement means for measuring positions of the alignment marks corresponding to the partial transfer patterns that belong to the divided groups; coordinate system determination means for determining actual coordinate systems of the partial transfer patterns that belong to the groups on the basis of measurement results of the measurement means; and alignment means for sequentially aligning the partial transfer patterns that belong to the group of interest to the transfer medium in units of groups on the basis of the coordinate system of the group of interest determined by the coordinate system determination means, and transfer is done every time alignment is made by the alignment means.
According to the eighth aspect of the present invention, a method of manufacturing a device using lithography, comprises the steps of: applying a resist on a substrate; transferring a pattern onto the resist by one of the above-mentioned transfer methods; and developing the resist transferred with the pattern.